This study is designed to evaluate the safety and efficacy of a single injection of NX-1207 for the treatment of biopsy-confirmed low risk localized (T1c) prostate cancer in patients currently undergoing active surveillance. Study participants currently on active surveillance will be randomized either to treatment with a single intraprostatic injection of NX-1207 (2.5 mg or 15 mg) followed by active surveillance or to no treatment (continued active surveillance). Blinded efficacy evaluation will be by a second post-treatment prostate biopsy.

Inclusion Criteria:

• T1c prostate cancer
• Gleason score ≤ 6 with no Gleason pattern of 4 or 5.
• Life expectancy ≥ 5 years.
• Single positive prostate biopsy core with ≤ 50% cancer
• PSA ≤ 10 ng/mL

Exclusion Criteria:

• Previous active treatment (such as surgery, brachytherapy, radiotherapy) for prostate cancer.
• Evidence of metastatic disease or previous positive bone scan.
• Previous hormonal therapy for prostate cancer.
• Use of certain concomitant medications, including 5 alpha reductase inhibitors (e.g. finasteride, dutasteride), androgen receptor blockers (e.g. flutamide, bicalutamide), immunosuppressants(such as Imuran™, Enbrel™, Remicade™, Humira™, etc.), anticoagulants(such as Coumadin™ or heparin), or chemotherapeutics.
• Previous surgical or invasive prostate treatments such as TURP, TUMT, TUNA, laser or any other minimally invasive treatment within the past 12 months.
• Pelvic irradiation.
• Urinary tract infection more than once in the past 12 months.
• Acute or chronic prostatitis in the past 12 months.
• Clinically significant renal or hepatic impairment.
• Bleeding disorder.
• Poorly controlled diabetes type 1 or type 2.
• Urinary retention in the previous 12 months.
• Self-catheterization for urinary retention.
• Post-void residual urine volume > 200 mL.
• Prior significant rectal surgery or any rectal condition with rectal stenosis or fistula.
• History of alcohol or substance abuse or dependence within the past 2 years.